Numerous types of aggressive electrical wire connectors for forming bared ends of electrical wires into a waterproof electrical connection are known in the art. One type of aggressive electrical connector relies on inserting the wires into a sealant located between a terminal block and a terminal screw and then squeezing the bared ends of the wire by rotating the terminal screw. The more the terminal screw is tightening the greater the squeezing and hence the better the electrical connection between the bared wire end and the terminal screw, however, one must take care shearing the terminal screw by over torquing the screw.
Another type of aggressive electrical wire connector is a twist-on wire connector that can be used to form a waterproof electrical connection through rotation of the electrical wires in a spiral shape housing containing a sealant. In the twist-on wire connector as well as in the terminal connector, in general, the more aggressive the rotation the greater the compression of the wire ends and hence an enhanced electrical connection between the electrical wires.
Another type of aggressive electrical wire connector, which is used with unstripped wires, is a cutting connector that uses two blades that slice through the insulation layer of the electrical wire and also cut into the sides of the wire, which is located in a waterproof sealant. In each of these prior connectors the electrical connection can be formed in the presence of a waterproof agent through use of a force sufficient to negate the presence of a waterproofing and electrically insulating agent located on and between the electrical wires.
Another type of electrical connector, which lacks aggressiveness, is a push-in wire connector. A push-in wire connector is a less aggressive wire connector since the force on the wire by the connector is generated by a fixed cantilevered mounted electrical conductor that flexes to allow insertion of an electrical wire between the conductor and a bus strip. An example of a push-in wire connector that shows one resilient spring is shown in U.S. Pat. No. 6,746,286 and an example of a push-in wire connector that includes two resilient springs for engaging an electrical wire to form an electrical connection as a wire is inserted in the connector is shown in U.S. Pat. No. 7,255,592.
The clamping force holding the wire in electrical contact with bus strip and the electrical conductor of the push-in wire connector are determined by the resilient force of the resilient springs and can not be increased by more aggressive action such as in twist-on wire connectors since the axial force applied to flex the resilient spring conductors in a push-in wire connector is limited by the stiffness of the wire. That is, to generate a clamping force on the electrical wire in a push-in wire connector the wire must be inserted in an axial direction, which is at 90 degrees to the direction of force generated by the resilient conductor. Thus, the resilient electrical conductor in a push-in wire connector must flex in response to one axially inserting a wire therein. The wire clamping force in the push-in wire connector is limited because the axial resistance of the resilient conductor must not be so large so as to bend the electrical wire during the insertion process. Consequently, clamping forces generated by push-in wire connectors lack the inherent aggressive nature of other connectors that can force sealant away from contact areas between conductors.
Although the push-in wire connectors lack the aggressiveness of other electrical wire connectors the push-in wire connector are simple to use since an electrical connection can be made in one continuous motion. That is, one axially inserts an electrical wire into a chamber in the push-in wire connector until the wire forms electrical engagement with a resilient conductor that automatically flexes to form pressure engagement with the electrical wire. Typically, in the push-in wire connector cylindrical elements of a cylindrical wire engage both a bus strip and a resilient conductor as they sandwich the electrical wire between a straight edge on the resilient wire conductor and the bus strip. However, the lack of an ability to increase the force on the contact regions between the edge, the bus strip and the wire limit the ability to enhance the electrical connection in a push-in wire through use of additional force and thus impair the electrical connection to withstand heat cycling.
If a waterproof heat cycleable electrical connection is required in a push-in wire connector the conventional methods of waterproofing are to either place an elastic bushing around the wire before the wire is inserted into the push-in wire connector to form a waterproof seal around the electrical wire or to inject a sealant in the push-in wire connector after the wire has been inserted into engagement with the electrical conductor and bus strip therein. In still another method of waterproofing push-in wire connectors the entire push-in wire connectors with the electrical wires therein is inserted into a housing containing a sealant which allows one to encapsulate the entire push-in wire connector and thereby waterproof the wire connections therein.
One of the difficulties in forming waterproof electrical connections is also ensuring that the electrical connection formed in the presence of the sealant is capable of withstanding the heat cycling that may occur during field use of the push-in wire connector.